Prewetting cellulosic fabric before introduction to dehydrating solution of formaldehyde reactant in a continuous process



March 5, 1968 R. P. BARBER ETAL 3,3 3

PREWETTING CELLULOSIC FABRIC BEFORE INTRODUCTION TO DEHYDRATING SOLUTIONOF FORMALDEHYDE REACTANT IN A CONTINUOUS PROCESS Filed Dec. 4, 1961 2Sheets-Sheet 1 INVENTOR QICHNZD P b/mbuz VEIZNOH G 5mm A'ITORNEYJ UnitedStates Patent v I 3,371,983 PIREWETTING CELLULOS IC FABRIC BEFORE IN-TRODUCTION T DEHYDRATING SOLUTION 0F FORMALDEHYDE REACTANT IN A CON-TINUOUS PROCESS Richard P. Barber, Mooresville, and Vernon C. Smith,Greensboro, N.C., assignors to Burlington Industries, Inc., Greensboro,N.C., a corporation of Delaware Continuation-impart of application Ser.No. 136,418, Sept. '5, 1961. This application Dec. 4, 1961, Ser. No.156,859

11 Claims. (Cl. 8-1164) This application is a continuation-in-part ofapplication Ser. No. 136,418, filed Sept. 5, 1961, now abandoned.

The present invention relates to a continuous method for treatingceliulosic fabrics with formaldehyde.

While formaldehyde has been employed in the past to treat cellulosicfabric, there is need for improving both the wet and dry wrinklerecovery. Furthermore, previous reactive type treatments of cellulosicfabrics, including formaldehyde treatments, degrade the fabric to anextent of over 50%.

Accordingly, it is an object of the present invention to develop animproved continuous process for treating cellulosic materials withformaldehyde.

Another object is to improve the wet wrinkle resistance of cellulosicfabrics.

A further object is to improve the dry wrinkle resistance of cellulosicfabric.

An additional object is to improve the wrinkle resistance of;cellulosicfabrics while retaining 5060% of the tensile strength.

,Yet another object is to improve the wrinkle resistance of cellulosicfabrics by a reactive procedure while at the same time retaining 70% ormore of the tensile strength of the fabric.

Still another object is to reduce the time of formaldehyde treatment forcellulosic fabrics.

Still further objects and the entire scope of applicability of thepresent invention will become apparent from the detailed descriptiongiven hereinafter; it should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

It has now been found that these objects can be attained by firsttreating the cellulosic fabric with a relatively dilute aqueous systemand substantially immediately thereafter treating the cellulosic fabricwith a formaldehyde solution of substantially lower water content.

,By pretreating the cellulosic fabric with water there is a swelling ofthe fabric to make it accessible for the subsequent reaction with theformaldehyde. As a result, the reaction with formaldehyde in the nextstep occurs more rapidly. The amount of water retained by the fabric inthis step should be between 10 and 100% by weight of the fabric. In thesecond step the water present in the formaldehyde solution should not beover 50% and preferably not over 20%. The solution in the second stepthus acts in the nature of a dehydrating agent in that it tends toextract the impregnated Water from the fabric while the formaldehydediffuses into and reacts with the cellulosic material. The formaldehydecontent of the solution is usually 5l0% but can be lower, e.g., 3%, orhigher, e.g.,

While the first step of the treatment is instantaneous, the second stepcan vary from instantaneous up to 5 minutes, the time of treatment beinginversely with the 3,371,983 Patented Mar. 5,1968

' ably 60-70%.

As a result of the two step treatment, there is obtained excellent wetcrease recovery together with good tensile strength retention. At thesame time the time of the formaldehyde reaction is greatly reduced overthat normally employed in past operations for treating the cellulosicfabric with formaldehyde.

As the cellulosic fabric there can be employed cotton, linen, hemp,jute, ramie, sisal, rayons, e.g., regenerated cellulose (both viscoseand cuprammonium, cellulose acetate, cellulose acetate-propionate,cellulose acetate-butyrate and ethyl cellulose and mixtures of suchcellulosic fabrics with each other or other fabrics, e.g., nylon,acrylonitrile fibers or polyester fabrics. The invention is particularlyapplicable to the treatment of cotton fabric material such as cottoncloth.

There are two general methodsv for carrying out the above set forthtwo-step procedure.

In the first method the cellulosic fabric is padded to a 10100%,preferably 60-70%, weight pick up of an aqueous solution of a strongacid, or the salt of a weak base with a strong acid, e.g., phosphoricacid, hydrochloric acid, hydrobromic acid, sulfuric acid,trichloroacetic acid, formic acid, toluene sulfonic acid, ammoniumchloride and ammonium sulfate. The acid strength can vary from moderateconcentrations, e.g., 20% to as low as 0.01%, but preferably is between0.5 and 6%. The preferred acid is hydrochloric acid, The acid treatedfabric substantially immediately thereafter is treated with theformaldehyde solution in the dehydrating solvent, e.g., glacial aceticacid or 70% calcium chloride. A small amount of acid, e.g., 0.01-2%, canbe added in the dehydrating solution if desired. Also, a portion of theformaldehyde can be added in the acid solution padded onto the fabric.However, a substantial portion of the formaldehyde, i.e., at least 50%should be added in the dehydrating solution. Since the initial paddingwith the acid solution is almost instantaneous and is usually carriedout at room temperature, there is no significant reaction until thefabric is placed in the dehydrating solution.

In the second method the cellulosic fabric is padded to a 10-100%,preferably 60-70%, weight pick up of a solution of water containing awetting agent, preferably 0.1- 1%. If the fabric is of the type whichWets out, the wetting agent can be omitted and plain water employed.While anionic and cationic wetting agents can be employed, the preferredwetting agents are nonionic in character.

Typical examples of nonionic wetting agents are alkylaryl polyetheralcohols such as Triton 155, p-isooctylphenol condensed with 10 ethyleneoxide units, Arlacel C (sorbitan sesquioleate), Brij 35 (polyethyleneglycol lauryl ether), Ethofats (polyethylene esters of fatty acidsorrosin acids, e.g.- Ethofat 3, 7, ll, 13, 15 and 19), Ethomids, e.g.,Ethomid 8, 10, 12 and 14, Igepal CA (alkylphenyl polyethylene glycolether), Myrj (polyethylene glycol stearate), Ninol 1281 (fatty acidethanolamide), Nonionic 218 (tertiary dodecyl polyethylene glycolthioether), Pluronics (condensation products of ethylene oxide andpropylene oxide having molecular weights of 400 to 4000), Span 20(sorbitan monolaurate), Span 40 (sorbitan monopalmitate), Span 60(sorbitan monostcarate), Span 8O (sorbitan monooleate), Sterox CD(polyethylene glycol ester of tall oil acids), Triton X- (p-octylphenylpolyethylene glycol ether), Tween 20 3 (tris polyoxyethylene sorbitanmonolaurate) and Tweens 40, 60 and 80 (the palmitates, stearates andoleates corresponding to the laurate of Tween 20).

There can also be employed anionic surface active agents such as alkyland aryl sulfates and sulfonates, e.g., sodium alkyl benzene sulfonateshaving to 18 carbon atoms, sodium lauryl sulfate, Aerosol OT (sodiumsalt of dioctyl sulfosuccinate), sodium oleyl isethionate, sodiumNmethyl-N-oleyl laurate, sodium salt of propylated naphthalene sulfonicacid, sodium salt of sulfonated monoglyceride of cocoanut fatty acids,Areskap 100 (sodium salt of butylphenylphenol sulfonic acid), sodiumlignin sulfonate, sodium dodecyl benzene sulfonate, sodium tetradecylsulfate and sodium dihexyl sulfosuccinate. As cationic surface activeagents there can be used lauryl trimethyl ammonium chloride, cetylpyridinium chloride and octadecyl trimethyl ammonium chloride.

After the fabric is padded with the water, with or without the wettingagent, the wet fabric substantially immediately thereafter isimpregnated with a dehydrating solution, e.g., anhydrous glacial aceticacid or an aqueous calcium chloride solution of concentration from 60%to saturation, e.g., 70%. The dehydrating solution con tains 5-10% offormaldehyde and also contains 0.01- of a strong acid, e.g.,hydrochloric acid or sulfuric acid or any of the other acids previouslyset forth. The reaction time with formaldehyde is dependent upon thetemperature in the same manner as in procedure 1.

Whether the first method or the second method i employed, it has beenfound that superior results are obtained by applying 248% of acrease-proofing resin. The crease-proofing resin can be applied beforeor after the formaldehyde treatment but is preferably applied first. Theaddition of the resin not only increases the dry wrinkle recovery anglebut also increases the wet crease angle. Thus, reaction of formaldehydeaided the resin in increasing the dry wrinkle recovery angle while theresin correspondingly aided the formaldehyde in increasing the wet anglerecovery. By using the resin treatment followed by the two stepprocedure of formaldehyde application of the present invention thedecrease in tensile strength of the fabric can be limited to This is amuch lower decrease in tensile strength than any of the previouslyemployed formaldehyde or other reactive type treatments of cellulosicfabric for improving wrinkle resistance.

As the resin there can be employed any of the curable crease-proofingresins. These include the urea-aldehyde, e.g., urea-formaldehyde resin,dimethylolurea, dimethyl ether of urea-formaldehyde resin,aminotriazine-aldehyde resins, e.g., melamine-formaldehyde resinsincluding alkylated melamine-formaldehyde, trimethylol melamine,methylated trimethylol melamine, tetrahydro-S-hydroxy- 2(1H)-pyrimidone-formaldehyde resin, cyclic ethylene ura-formaldehyde,e.g., dimethylol ethylene urea, uronformaldehyde resins, e.g.,dimethylol uron, Aerotex 23 (a triazine-formaldehyde resin believed tobe a melamineformaldehyde type resin), Rohm and Haas Resin N-17 (atriazone-formaldehyde resin, e.g., dimethylol ethyl triazone), Dextraset48 (a urea-formaldehyde resin), Eponite 100 (believed to be a butadienediepoxide). Other polyepoxides can be used including bisphenol-Aepichlorhydrin, 1,4-bis (2,3-epoxypropoxy) benzene, 1,3- bis(2,3-epoxypropoxy) octane, ethylene glycol diglycidyl ether, as well asany of the other polyepoxidcs set forth in Schroeder et al. Patent2,774,691. Other crease-proofing agents such as those set forth inTextile Industries," October 1959, pp. 116-127, can also be used.

The time and temperature for curing the resins are those convenientlyemployed in the art. For convenience, cures at 350 F. (178 C.) for 1V2minutes were employed in the specific examples.

Unless otherwise indicated, all parts and percentages are by weight.

In the drawings:

FIGURE 1 is a schematic diagram of a preferred'continuous operationaccording to the invention; and

FIGURE 2 is a schematic diagram of an alternative continuous operation.

Referring to FIGURE 1, the cotton cloth was passed substantiallyinstantaneously through the resin padding tank 1 containing, forexample, an aqueous solution :of melamine-formaldehyde. The cloth pickedup 4% of resin. It then went to drier 2 where it remained for 1 /2minutes at 300 F. (149 C.) and then to the curing oven 3 where itremained for 1 /2 minutes at 350 F. (178" C). The cotton clothcontaining the cured resin next went substantially instantaneouslythrough formaldehyde catalyst padding solution 4 which was 1.5% aqueoushydrochloric acid at room temperature. The cloth picked up approximately60-70% of its own weight of the acid solution and then passed intoformaldehyde reactor 5 maintained at C. The reactor contained 70%calcium chloride, 5% formaldehyde and 25% water. It took 30 seconds forthe cloth to run through the reactor. The fabric was then treated inconventional fashion by passing through 10% aqueous ammonia for 30seconds in neutralization chamher 6 and then washed in water for 30seconds in washing operation 7. The cloth was then dried in drier 8 forseveral minutes at NO C. to remove the water.

Referring to FTGURE 2, the cotton cloth was passed substantiallyinstantaneously through the formaldehyde catalyst padding solution 9containing 2% aqueous hydrochloric acid at room temperature. The clothpicked Lp of its own weight of the acid solution and then passed intoformaldehyde reactor 10 maintained at 50 C. The reactor contained 8%formaldehyde dissolved in anhydrous glacial acetic acid, It took aboutone minute for the cloth to run through the reactor. The fabric thenpassed through 10% aqueous ammonia for 30 seconds in neutralizationchamber 11 and then was Washed with water for 30 seconds in washingoperation 12 and dried for several minutes at 110 C. in drier 13. Thedried formaldehyde treated fabric then passed substantiallyinstantaneously through resin padding tank 14 containing, for example,an aqueous solution of methylated ureaformaldehyde. The cloth picked up6% of resin. It then went to drier 15 where it remained for 1 /2 minutesat 300 F. (149 C.) and then to the curing oven 16 where it remained for1 /2 minutes at 350 F. (178 C.). The cotton cloth was then washed inwashing operation 17 to remove any remaining acid and again dried.

Table 1 shows the results obtained by treating cotton cloth with anaqueous solution of hydrochloric acid to a pick up of 6070% of theweight of the fabric followed by reaction with a glacial acetic acidsolution containing 8% formaldehyde. No resin treatment was utilized.Examples 2-6 in the table are in accordance with the invention andExamples 1 and 7 are controls. Example 7 shows the properties of thecloth without any treatment.

TA B LE 1 Temperature Time Pad Solution Tensile Stren th, Wet Wrinkle ReExample C.) (m (60-70% Pickup) W & F (lbs. eovery, W & F

(Monsanto) 1.. 5 water 63 X 51 2.88 X 2.82 90 1 0.6% HCL- 37 X 25 3.65 X3.62 70 1 1. 0% HC] 37 X 25 3. 58 X 3.5 70 1 0.5% HC 43 X 34 3.48 X 3.4550 1 1.5% HCl 50 X 30 3.3 X 3.3 30 1 0.0% HCl 44 X 35 3. 44 X 3.4 l 61 X51 3.0 X 2.90

Table 2 shows the results obtained by treating cotton productv had atensile strength (lbs) 47 x 37 (W & F), cloth with a 1% aqueous solutionof Triton 155 (higher dry wrinkle recovery W & F)' of 2.7 x 3.0 and awet alkyl aryl monoether of polyethylene glycol) to a pick wrinklerecovery (W & F) of 3.52 x 3.52. 1 up of 60-70% of the weight of thefabric followed by reaction with a glacial acetic acid solutioncontaining 8% formaldehyde and the indicated amounts of HCl. Ex- Cottoncloth was Padded Wlth 1% aqueous Hcl to 3 Example 31 amples 8-18 are inaccordance with the invention. Ex- E was imfniidlately theriafler ample19 is a comparison example wherein the cotton Pfegnated Wlth a Solutloncontammg 70% f cloth was in the dry state before entering theformalder1c 1e10% formaldehydefand-zoqa' water at fen /2 hyde reactor(i.e., there was no previous water pick up) minuteand Example 20 showsthe properties of the cloth with- Example 32 out any treatment. Cotton:cloth was padded in a substantially instantane- TABLE 2 Temperature n ilrength Wet Wrinkle Example C.) 1 Time (min) Percent HCl Filling (lbs.)Recovery, W dz F (Monsanto) 90 0. 5 l8 3. 72x3. 67 90 1 0. 5 3. 93x3. 9370 1 0. 5 24 3. 73x3. 75 50 1 0.5 31 3.4 x3. 52 1 0.5 39 3.2 x3. 2 90 30.01 34 3.5 3.4 70 3 0.05 31 3.5 3.4 50 3 0.2 27 3.5 x 70- 0.4 27 3.5x35 70 2. 0 23 3. 70x3. 74 30 5 2. 0 33 3. 63x3. 65 30 5 2. 0 32 2.32x3. 09 2o 51 3. 05x2. 90

Table 3 shows the results obtained by padding cotton cloth with 6.0%aqueous hydrochloric acid to a pick up of 60-70% by weight of the clothfollowed by impregnaous manner with 1.3% of aqueous-HCl at roomtempertion with 8% formaldehyde in glacial acetic acid for 1-3 35 atureto a pick up of 60-70% by weight of the fabric. minutes at 30-35 C.followed by neutralization, washing The cloth then passed through asolution containing 60% and drying and then padding with an aqueous.solution calcium chloride, 5% formaldehyde, 1% HCl and 34% of Aerotex 23resin to a pick up of 10% by weight of the water for 45' seconds at 50C. The product had the cloth in Examples 21-24 and to a pick up of 8% infollowing properties:

Examples 26-29. Example 25 was a comparison example wherein the fabricwas treated only with 10% of the Tensil strength (filler) lbs 33 resin(no formaldehyde treatment). In Examples 21-29 Dry wrinkle recovery (W&F) 3.1 x 2.8 after the resin padding operation, the cloth was dried Wetwrinkle recovery (W & F) 3.4 x 3.5 for 1 /2 minutes at 300 F. (149 C.)and then cured Formaldehyde pick up percent 0.354 for 1 /2 minutes at350 F. (178 C.).

Table 4 shows the results obtained using the procedure TABLE 3illustrated in FIGURE 1 with four different commercially TensileStrength, Dry wrinkle Wet wrinkle available crease-proofing resins. Theresins were padded X 2? a fig ig f f F z m sg g f F onto the cottoncloth in an amount of 8%, the cloth dried for 1 /2 minutes at 300 F.(149 C.) and then cured at 22:33 -g gi-g 2 2 350 F. (178 C.) for 1 /2minutes. The cloth was then 45x25 5,; j x3153 padded with 1.5% aqueousHCl followed immediately g3 g2 33 i g: g; i 33 by impregnation with amixture of 70% calcium chloride, 46x29 5 1. 1 1 5% formaldehyde, 0.2%HCl and the balance water at 2333?. 3133131 53 313333 5 8 55 1 mute-40x27 3.511430 3.58x3.61

TABLE 4 Tensile Dry Wrinkle Wet Wrinkle Strength Recovery, W dz FRecovery, W &F Example Resin (Filling) lbs.

33 Aerotex 23 32 3 1 x 3.08 3. 67x 3.58 Rhonite N-17 34 3 0 x 3. 0 3.38x 3. 4s Dextraset 4s 35 3 is x 3.09 3.45 x 3. 4s 3s Eponlte 100 37 2 82x 2.85 3.33 x 3. 32

Example 30 In the present specification and claims when the percent ofcalcium chloride is referred to it is calculated as Using the procedureshown in FIGURE 1, there was calcium chloride hexahydrate which is thecommercially padded onto cotton cloth 4% of Aerotex 23. The resinavailable form.

was cured for 1 /2 minutes at 350 F. (178 C.). There We claim:

was then padded on the cloth a 1% aqueous HCl solu- 1. A continuousprocess for increasing the wet wrinkle tion to a pick up of 60-70% byweight of the cloth recovery of a cellulosic fabric comprising treatingthe followed by impregnation with 8% formaldehyde in fabric with anaqueous medium in which water is the sole glacial acetic acid for 2minutes at 50 C. There was a essential liquid until the fabric contains10-100% of its pick up of 0.670% formaldehyde on the fabric. The ownweight of added water, substantially immediately 7 thereafter passingthe wet fabric into a dehydrating solution of formaldehyde at atemperature up to 90 C. for a period of up to 5 minutes whereby theformaldehyde reacts with said fabric to improve the wet wrinklerecovery, Washing the thus treated fabric with water and then dryingsaid fabric.

2. A process according to claim 1 in which the fabric is a cottonfabric.

3. A process according to claim 1 wherein the dehydrating solution isone selected from the group consisting of (a) an aqueous solutioncontaining at least 50% calcium chloride, calculated as calcium chloridehexahydrate, and at least 3% formaldehyde; and (b) anhydrous acetic acidcontaining at least 3% formaldehyde.

4. A process according to claim 3 wherein the treatment withformaldehyde is carried out in the presence of an acid catalyst and thefabric, directly after the formaldehyde treatment, is passed through anacid-neutralizing bath and then washed and dried.

5. A process according to claim 4 wherein the acid catalyst is presentin the aqueous medium and said medium includes not more than 50% of theformaldehyde requirements for said process.

6. A process according to claim 4 wherein the acid catalyst is in thedehydrating solution and the aqueous medium includes a fabric wettingagent.

7. A process according to claim 4 including the application of acrease-proofing resin to said fabric prior to the formaldehydetreatment.

8. A process according to claim 4 including the application of acrease-proofing resin to said fabric after the formaldehyde treatment.

9. The process of claim 4 wherein said acid catalyst is hydrochloricacid, and the dehydrating solution is an aqueous solution of calciumchloride at a temperature of 5090 C.

10. The process of claim 9 wherein the treatment with said dehydratingsolution takes from 30 seconds to 1 minute,

11. The process of claim 10 wherein the cloth is kept in open widththroughout.

References Cited UNITED STATES PATENTS 2,080,043 5/1937 Heckert 8-116.3

995,852 6/1911 Eschalier 8-116.4 2,338,983 1/1944 Thackston 8-116.32,593,207 4/1952 Silver 8-116.3 3,046,079 7/ 1962 Reeves 8116.42,689,194 9/1954 Russell 8-116.4 X 2,922,768 1/ 1960 Mino et a1.2,243,765 5/1941 Morton 8116.4 3,189,404 6/1965 Takizaki et al. 8-11643,175,875 5/1965 Gagarine 8116.4 X 3,265,463 8/1966 Barber et al. 8116.4X 3,038,777 6/1962 Daul et al. 8116.4

FOREIGN PATENTS 462,005 3/ 1937 Great Britain, 568,258 3/1945 GreatBritain.

Datye et al., Textile Research Journal, vol. 30, 72-73 January 1960.

Reeves et al., Textile Research Journal vol. 30, 179-192 March 1960.

Daul et al., Textile Research Journal, vol. 23, 738-747 August 1954.

J. TRAVIS BROWN, Acting Primary Examiner.

A. LOUIS MONACELL, J. S. LEVITT, J. T. BROWN,

Examiners. J. CANNON, Assistant Examiner.

1. A CONTINUOUS PROCESS FOR INCREASING THE WET WRINKLE RECOVERY OF ACELLULOSIC FABRIC COMPRISING TREATING THE FABRIC WITH AN AQUEOUS MEDIUMIN WHICH WATER IS THE SOLE ESSENTIAL LIQUID UNTIL THE FABRIC CONTAINS10-100% OF ITS OWN WEIGHT OF ADDED WATER, SUBSTANTIALLY IMMEDIATELYTHEREAFTER PASSING THE WET FABRIC INTO A DEHYDRATING SOLUTION OFFORMALDEHYDE AT A TEMPERATURE UP TO 90*C. FOR A PERIOD OF UP TO 5MINUTES WHEREBY THE FORMALDEHYDE REACTS WITH SAID FABRIC TO IMPROVE THEWET WRINKLE RECOVERY, WASHING THE THUS TREATED FABRIC WITH WATER ANDTHEN DRYING SAID FABRIC.